Electronic still camera with lessened power consumption

ABSTRACT

In an electronic still camera of the kind having a detachably mounted photo-taking optical system, an image sensor which converts into an electrical video signal an object image formed by the photo-taking optical system, a recording circuit which records the video signal and an electronic viewfinder which displays an image represented by the video signal obtained by the image sensor when the camera is in a shootable state, a confirmation member is arranged to confirm a mounted or detached state of the photo-taking optical system, and a driving-suspending and displaying-off control circuit is arranged to suspend a driving action on the image sensor and to turn off the electronic viewfinder when the detachment of the photo-taking optical system from the camera body is confirmed by the confirming member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a electronic still camera and moreparticularly to a camera of the kind arranged to record, on a recordingmedium, images obtained by image sensing means such as a solid-stateimage sensor.

2. Description of the Related Art

An electronic still camera has recently been developed. The electronicstill camera comprises in combination a solid-state image sensor such asa CCD and a recorder using a rotary recording medium such as a magneticdisc. The camera is arranged to record a still image on the rotaryrecording medium and to reproduce the recorded image using a monitor ora printer.

Unlike the camera of the kind using a silver-halide film (hereinafterreferred to as a silver-halide camera), the electronic still cameraobviates the necessity of chemical processes such as a developingprocess, etc. An image obtained by the image sensor is instantlyobservable on a monitor or as a hard copy. It is not necessary to shieldthe recording medium from light. Further, the recording medium isreusable. The electronic still camera thus has many advantages. It isanother advantage of the electronic still camera that the camera of thiskind permits use of an electronic viewfinder. The use of the electronicviewfinder obviates the necessity of having a quick return mirror, etc.,arranged between a photo-taking optical system and the image sensor.Besides, the camera of this kind is free from the following problems ofthe silver-halide camera of the kind having a viewfinder optical systemseparately from the photo-taking optical system: There arises adifference in parallax between the two optical systems. In a case wherethe photo-taking optical system is a zoom lens, it necessitates acomplex interlocking mechanism between the two optical systems.

However, a disadvantage of the electronic viewfinder of the conventionalelectronic still camera lies in that, unlike the optical viewfinder, itconsumes a large amount of electric energy. Therefore, the conventionalelectronic still camera using the electronic viewfinder has greatlyshortened the life of a power source because of the large electricenergy consumption by the electronic viewfinder.

SUMMARY OF THE INVENTION

This invention is directed to the solution of the above-stated problem.It is, therefore, a first object of the invention to provide anelectronic still camera which is arranged to prevent any unnecessaryconsumption of electric energy by stopping a driving action on imagesensing means and by turning off an electronic viewfinder in a casewhere the photo-taking optical system is detached from a camera body,thus requiring no displaying by the electronic viewfinder, while thecamera is in a shootable state.

It is a second object of the invention to provide an electronic stillcamera which is arranged to turn off an electronic viewfinder during aperiod between the start and end of a self-timer shooting operation forthe purpose of preventing the camera from unnecessarily consuming thepower source thereof.

It is a third object of the invention to provide an electronic stillcamera which is arranged to prevent an unnecessary consumption of thepower source of the camera by suspending a driving action on imagesensing means and by turning off an electronic viewfinder during theperiod of an interval shooting mode except when shooting and recordingactions are performed.

It is a fourth object of the invention to provide an electronic stillcamera which is arranged to prevent an unnecessary consumption of thepower source of the camera by suspending a driving action on imagesensing means and by turning off an electronic viewfinder during theperiod of a remote-control shooting mode except when shooting andrecording actions are performed.

To attain this object, an electronic still camera of the kind having adetachably mounted photo-taking optical system, image sensing means forconverting into an electrical video signal an object image formed by thephoto-taking optical system, recording means for recording the videosignal and an electronic viewfinder for displaying an image representedby the video signal obtained by the image sensing means at the time of ashootable state of the camera is arranged according to this invention asan embodiment thereof to comprise: confirming means for confirming adetached state or mounted state of the photo-taking optical system; anddriving-suspending and displaying-off control means arranged to suspenda driving action on the image sensing means and to turn off theelectronic viewfinder when the confirming means confirms that thephoto-taking optical system is detached from the camera at the time of ashootable state of the camera.

The embodiment which attains the above-stated object is arranged to turnon the electronic viewfinder again when the photo-taking optical systemis mounted again on the camera body after the electronic viewfinder isturned off with the photo-taking optical system detached from the camerabody at the time of a shootable state of the camera, so that the imagerepresented by the video signal obtained by the image sensing means canbe displayed.

The above-stated electronic still camera arranged according to thisinvention confirms by the confirming means a mounted or detached stateof the photo-taking optical system on or from the camera body; andsuspends a driving action on the image sensing means and turns off theelectronic viewfinder by the driving-suspending and displaying-offcontrol means upon confirmation of the detached state of the opticalsystem from the camera body at the time of a shootable state of thecamera. Further, with the electronic viewfinder remaining turned offwhile the photo-taking optical system is dismounted, when the opticalsystem is again mounted on the camera body at the time of a shootablestate, the electronic viewfinder comes to be turned on again to displaythe image represented by the video signal obtained by the image sensingmeans.

Further, to attain the above-stated object, an electronic still camerahaving a photo-taking optical system, image sensing means for convertinginto an electrical video signal an object image formed by thephoto-taking optical system, recording means for recording the videosignal, an electronic viewfinder for displaying an image represented bythe video signal obtained by the image sensing means at the time of ashootable state of the camera and self-timer shooting means having aself-timer shooting function is arranged according to this invention asan embodiment thereof to include: displaying-off control mean forturning off the electronic viewfinder when a self-timer shooting actionbegins with the camera set in a self-timer shooting mode.

In the embodiment, the displaying-off control means turns on theelectronic viewfinder again to display an image represented by the videosignal obtained by the image sensing means after completion of theself-timer shooting action. With the electronic still camera providedwith the displaying-off control means, the electronic viewfinder isturned off when the self-timer shooting action begins with the cameraset in the self-timer shooting mode by the self-timer shooting functionof the self-timer shooting means. Further, the displaying-off controlmeans of the electronic still camera is arranged to again turn on theelectronic viewfinder upon completion of the self-timer shooting actionto display the image represented by the video signal obtained by theimage sensing means.

Further to attain the above-stated object, an electronic still camerahaving a photo-taking optical system, image sensing means for convertinginto an electrical video signal an object image formed by thephoto-taking optical system, recording means for recording the videosignal and an electronic viewfinder for displaying an image representedby the video signal formed by the image sensing means is arranged as anembodiment of this invention to comprise: interval shooting means forautomatically performing a shooting action at intervals of a givenperiod of time and for a number of pictures designated from the outside;and driving-suspending and displaying-off control means arranged tosuspend a driving action on the image sensing means and to turn off theelectronic viewfinder at the time other than the time of shooting andrecording actions after commencement of interval shooting with thecamera set in an interval shooting mode.

The above-stated electronic still camera is arranged to be set by theinterval shooting means into an interval shooting mode in which intervalshooting is performed for a number of pictures and at intervals of timedesignated from the outside; and, after commencement of the intervalshooting, to suspend the image sensor driving action and to turn off theelectronic viewfinder by the driving-suspending and displaying-offcontrol means except for photo-taking and recording actions.

Further to attain the above-stated object, an electronic still camerahaving a photo-taking optical system, image sensing means for convertinginto an electrical video signal an object image formed by thephoto-taking optical system, recording means for recording the videosignal, an electronic viewfinder for displaying an image represented bythe video signal obtained by the image sensing means at the time of ashootable state of the camera and a remote-control shooting function isarranged as an embodiment of the invention to comprise: remote-controlmode setting means for setting the camera into a remote-control shootingmode; and driving-suspending and displaying-off control means arrangedto suspend a driving action on the image sensing means and to turn offthe electronic viewfinder when the camera is set in the remote-controlshooting mode.

In the arrangement described above, the remote-control mode settingmeans includes a remote-control operation member which is engageablewith the camera body and engagement confirming means for confirming thatthe remote-control operation member is engaged with the camera body. Thecamera is brought into the remote-control shooting mode by theremote-control mode setting means when the engagement confirming meansconfirms that the remote-control operation member is detached from thecamera body at the time of a shootable state of the camera.

Further, in the above-stated arrangement, the remote-control modesetting means is allowed to set the camera into the remote-controlshooting mode by means of a remote-control shooting mode setting switchwhen the camera is in a shootable state. The above-stated object isattained with the remote-control member arranged discretely from thecamera body for remote-control shooting.

With the electronic still camera arranged as described above, the camerais set into the remote-control shooting mode by the remote-control modesetting means. With the camera set in the remote-control shooting mode,the driving-suspending and displaying-off control means suspends thedriving action on the image sensing means and turns off the electronicviewfinder in the remote-control shooting mode except when shooting andrecording actions are performed.

The remote-control mode setting means of the electronic still cameraaccording to this invention is arranged to set the camera in theremote-control shooting mode only after confirmation by the engagementconfirming means of the fact that the remote-control operation member isdetached from the camera body. Further, the remote-control mode settingmeans is arranged to set the camera in the remote-control shooting modewhen the camera is in a shootable state. After that, remote-controlshooting can be performed by means of the remote-control operationmember which is arranged discretely from the camera body.

These and further objects and features of the invention will becomeapparent from the following detailed description of embodiments thereoftaken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration showing in outline the arrangement ofan electronic still camera arranged as a first embodiment of thisinvention. FIG. 2 is a block diagram showing the arrangement of thefirst embodiment. FIG. 3 is a flow chart showing the flow of controlover the operation of the first embodiment.

FIG. 4 is a schematic illustration of the arrangement of an electronicstill camera arranged as a second embodiment of the invention. FIG. 5 isa flow chart showing the flow of control over the operation of thesecond embodiment. FIG. 6 is a schematic illustration of the arrangementof an electronic still camera arranged as a third embodiment of theinvention. FIG. 7 is a flow chart showing the flow of control over theoperation of the third embodiment. FIG. 8 is a schematic illustration ofthe arrangement of an electronic still camera arranged as a fourthembodiment of the invention. FIGS. 9(a) and 9(b) are flow charts showingthe flow of control over the operation of the fourth embodiment. FIGS.10(a) and 10(b) are oblique views showing the electronic still camera asin a remote-control shooting mode, FIG. 10(a) showing the camera bodyand FIG. 10(b) showing the remote-control operation member of the stillcamera.

FIG. 11 is a schematic illustration of a electronic still camera whichis arranged as a fifth embodiment of the invention. FIG. 12 is a blockdiagram showing the circuit arrangement of the fifth embodiment. FIGS.13(a) and 13(b) are flow charts showing the flow of control over theoperation of the fifth embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of this invention are described below withreference to the accompanying drawings:

Referring to FIGS. 1 and 2, image sensing means A1 is composed of animage sensor 4 and is arranged to convert into an electrical videosignal an object image which is formed by a photo-taking opticalsystem 1. Recording means B1 is composed of a recording part and isarranged to record the above-stated video signal. Confirming means C iscomposed of an interchangeable lens detection unit 12 and is arranged toconfirm a mounted or detached state of the photo-taking opticalsystem 1. Driving-suspending and displaying-off control mean D iscomposed of a camera control circuit 26 and is arranged to cause adriving action on the image sensing means A1 to be suspended and anelectronic viewfinder 5 to be turned off when it is confirmed by theconfirming means C that the optical system 1 is detached from the camerabody. The illustration includes a camera body unit A; an interchangeablelens unit B; an iris 2 which is controlled by an iris control circuit14; a shutter 3 which is controlled by a shutter control circuit 21(FIG. 2); an electronic viewfinder 5; a lens 6 of the viewfinder part; aswitch 7 which serves as a power supply switch and also as a modeselection switch; a mount 8 which is disposed on the side of the camerabody unit A; a mount 9 which is disposed on the side of theinterchangeable lens unit B; an electrical signal contact 10 which iscarried by the mount 8 of the camera body unit A; and another electricalsignal contact 11 which is carried by the mount 9 of the interchangeablelens unit B.

The first embodiment which is arranged in the above-stated manneroperates as described below with reference t FIGS. 1 and 2:

The camera becomes operable when the power supply is switched on withthe switch 7 operated. Then, the interchangeable lens detection unit 12makes a check to find if an interchangeable lens is mounted on thecamera body. If not, the electronic viewfinder 5 is not turned on. If aninterchangeable lens is found by the interchangeable lens detection unit12 to have been mounted on the camera body, the image sensor 4 isdriven, the electronic viewfinder 5 is turned on, and the viewfinder 5displays an image formed on the image sensor 4 by the photo-takingoptical system 1. At this moment, the shutter 3 is in an open state. Theiris 2 is opened and closed according to the electric charge which isaccumulated by the image sensor 4, i.e., the quantity of light incidentupon the image sensor 4. The aperture of the iris 2 is thus adjusted tohave a given quantity of light incident upon the image sensor 4. Thephotographer pushes a (shutter) release button (not shown) aftercomposing a picture through the electronic viewfinder 5. Then, when therelease button is pushed to its half stroke position, a switch SW1 (FIG.2) is turned on to allow a light measuring unit which is not shown tomeasure the luminance of an object to be shot. After that, a switch SW2(FIG. 2) is turned on when the release button is further pushed. Ashooting action begins when the on-state of the switch SW2 is confirmedby the camera control circuit 26. The aperture position of the iris 2 isfirst shifted to its position corresponding to an aperture value whichis either set according to the luminance of the object of set beforehandby the photographer. At the same time, the shutter 3 is closed and theelectric charge accumulated by the image sensor 4 is discharged. A videosignal which is thus obtained at the image sensor 4 by operating theshutter 3 is then transferred by the camera control circuit 26 to therecording part. The video signal is recorded by the recording partcontrol circuit 24 on an unrecorded part of the recording medium. Thenshutter 3 is brought back to its state obtained before the shutterrelease, and the shooting operation comes to an end.

When the camera is in a shootable state with the interchangeable lensmounted and the power supply of the camera switched on, the image sensor4 is driven and the electronic viewfinder 5 is turned on. Under thiscondition when the interchangeable lens is detached from the camera bodyfor the purpose of replacing it with another lens, the interchangeablelens detection unit 12 detects the absence of the interchangeable lensfrom its position on the camera body. Upon detection of this, thedriving action on the image sensor 4 comes to a stop and the electronicviewfinder 5 is turned off. After that, when the interchangeable lensdetection unit 12 comes to detect that an interchangeable lens ismounted again on the camera body, the electronic viewfinder 5 is turnedon to display an image formed at the image sensor 4.

Further, when none of camera operation members such as the releasebutton, etc., have been operated over a certain given period of time,the image sensor 4 ceases to be driven and the electronic viewfinder 5is turned off to prevent electric energy from being wasted. However,when a camera operation member is operated under this condition, theimage sensor 4 is driven and the electronic viewfinder 5 is again turnedon.

Next, the following describes control over the operation of the firstembodiment with reference to FIG. 3 which is a flow chart. Referring toFIG. 3, the flow of operation begins with the power supply switched on.Then, at a step 3a, a check is made to see if the interchangeable lensis mounted on the camera body. If so, the flow proceeds to a step 3b. Atthe step 3b: The image sensor is driven and the electronic viewfinder isturned on. The shutter is opened, and automatic iris control isperformed. If no interchangeable lens is found to be mounted on thecamera body at the step 3a, the flow comes back to the start of the step3a. At a step 3c: A check is made again for the mounted state of theinterchangeable lens. If the lens is found to be mounted, the flow comesto a step 3e. If not, the flow comes to a step 3d. At the step 3d: Thedriving action on the image sensor and the electronic viewfinder areturned off. The shutter is closed. A driving action on the iris comes toa stop. At the step 3e: A check is made to see if the switch SW1 ispushed. If so, the flow proceeds to a step 3f. If not, the flow comesback to the step 3c. At the step 3f: Light and distance measuringactions and white balance adjustment are performed and the flow proceedsto a step 3g. At the step 3g: A computing operation is performed toobtain a shutter speed, an aperture value and a degree to which theoptical system is to be moved. The flow then proceeds to a step 3h. Atthe step 3h: A check is made to see if the switch SW2 is turned on. Ifso, the flow comes to a step 3j. If not, the flow comes to a step 3i. Atthe step 3i: A check is made to see if the switch SW1 is on. If so, theflow comes back to the step 3h. If not, the flow comes back to the step3c. At the step 3j: The shutter is closed and the flow comes to a step3k. At the step 3k: The electric charge of the image sensor isdischarged. The position of the iris and that of the optical system areadjusted, and the flow comes to a step 31. At the step 31: The shutteris opened and closed. At a step 3m: The electric charge is transferred.At a step 3n: Recording is performed. At a step 3p: The shutter isopened. Automatic iris control is performed. A round of shootingprocesses comes to an end. The flow then comes back to the step 3c torepeat the same steps.

As described above, the first embodiment of this invention is arrangedto suspend the driving action on the image sensor and to turn off theelectronic viewfinder to save the power source from being unnecessarilyconsumed when the use of the electronic viewfinder is not required withthe photo-taking optical system detached from the camera body while thecamera is in a shootable state.

FIG. 4 shows in outline the arrangement of an electronic still camerawhich is arranged according to this invention as a second embodimentthereof. FIG. 5 is a flow chart showing control procedures for theoperation of the second embodiment.

In FIG. 4, the same component parts as those of the first embodimentshown in FIGS. 1 to 3 are indicated by the same reference numerals.Referring to FIG. 4, self-timer shooting means 28 is composed of aself-timer 29 and is arranged to permit self-timer shooting. Whenself-timer shooting begins with the camera set in a self-timer shootingmode, the camera control circuit 26 turns off the electronic viewfinder.

The flow of operation control procedures of the second embodiment isdescribed below with emphasis placed on the displaying-off control ofthe viewfinder:

The flow of operation control begins when the power supply of the camerais switched on. At a step 4a (FIG. 5) of the flow: Both the image sensorand the electronic viewfinder are turned on. An image is displayed atthe viewfinder. The shutter is opened. An automatic iris control actionis performed. The flow then proceeds to a step 4b. At the step 4b: Acheck is made to see if the switch SW1 has been pushed. If so, the flowcomes to a step 4c. If not, the flow comes back to the start point ofthe step 4b. At the step 4c: Light and distance measuring actions areperformed. A check is made for power supply voltage and for whitebalance. At a step 4d: A computing operation is performed for a shutterspeed, an aperture value and an optical system moving degree. At a step4e: A check is made to see if the switch SW2 has been pushed. If so, theflow proceeds to a step 4f. If not, the flow comes to a step 4g. At thestep 4g: A check is made to see if the switch SW1 is on. If so, the flowcomes back to a step 4e. If not, the flow comes back to the step 4b. Atthe step 4f: A check is made to see if the shooting mode is theself-timer shooting mode (hereinafter referred to as self-timer mode).If the mode is found to be a normal mode and is not the self-timer mode,the flow comes to a step 4h. At the step 4h: The shutter is closed andthe flow

comes to a step 4p. At the step 4p: The electric charge accumulated atthe image sensor is discharged. The position of the iris and that of theoptical system are moved. At a step 4q: The shutter is opened andclosed. At a step 4r: The electric charge of the image sensor istransferred. At a step 4s: Recording is performed and the flow proceedsto a step 4t. At the step 4t: The shutter is opened and the automaticiris control is performed. The flow then comes back to the step 4b.

Meanwhile, if the mode is found to be the self-timer mode at the step4f, the flow comes to a step 4i. At the step 4i: A timer is driven. Theelectronic viewfinder is turned off. At a step 4j: The shutter isclosed. At a step 4k: The electric charge of the image sensor isdischarged. The position of the iris and that of the optical system aremoved. The flow proceeds to a step 41. At the step 41: The shutter isopened and closed. At a step 4m: The electric charge is transferred. Ata step 4n: Recording is performed and the flow comes back to the step4a.

The second embodiment described above is capable of preventing the powersource from being unnecessarily consumed because the electronicviewfinder is turned off during a period of time from the start to theend of the self-timer shooting mode.

FIG. 6 shows in outline the arrangement of an electronic still camerawhich is arranged as a third embodiment of the invention. FIG. 7 is aflow chart showing the flow of control over the operation of the thirdembodiment. In FIGS. 6 and 7, the same parts as those of FIGS. 1 to 5are indicated by the same reference numerals.

Referring to FIG. 6, a camera control circuit 26 is arranged to causeinterval shooting to be automatically performed for a number of picturesand at intervals of a given period of time designated from the outside;and to suspend a driving action on the image sensor 4 and to turn offthe electronic viewfinder 5, except when shooting and recording areperformed, after commencement of an interval shooting operation with thecamera having been set in an interval shooting mode.

More specifically, in carrying out the interval shooting operation, thephotographer shifts the position of a switch 30 to select the intervalshooting mode. The photographer also sets the interval time (time K) andthe number of pictures (N) to be shot; and then determines the picturecomposition in the same manner as in the case of the normal shooting.(The picture composition may be determined before the setting of theinterval shooting mode.) After commencement of the interval shootingmode, the image sensor driving action is suspended and the electronicviewfinder is turned off except when shooting and recording actions areperformed. The shooting process of the camera, from the light measuringaction to the recording action, is performed in the same manner as inthe case of the normal shooting operation.

The following describes the operation control flow of the thirdembodiment with reference t the flow chart of FIG. 7 and with emphasisplaced on the driving-suspending and displaying-off control means: InFIG. 7, the same steps as those of FIG. 5 are indicated by the same stepnumbers. At a step 5a of FIG. 7, a check is made to see if the shootingmode is the interval shooting mode. If it is found to be a normalshooting mode and is not the interval shooting mode, the flow proceedsto a step 4h and subsequent steps. If the shooting mode is the intervalshooting mode, the flow proceeds to a step 5b. At the step 5b: A drivingaction on the iris is stopped. A shot count number "n" is set at "0".The electronic viewfinder 5 is turned off. The flow proceeds to a step5c. At the step 5c: The shot count number "n" is set at "n+1"(incremented by one). The shutter 3 is closed. At a step 5d: Theelectric charge of the image sensor 4 is discharged. At a step 5e: Theposition of the iris and that of the optical system 1 are moved. At astep 5f: The shutter is operated. At a step 5g: The electric charge istransferred. At a step 5h: The recording action is performed. Step 5i: Acheck is made to see if the shot count number "n" is less than a setnumber of shots N. If so, the flow comes to a step 5j. At the step 5j:The flow waits for a set interval period of time K. After the end of thewaiting time, the flow comes back to the step 5e to repeat theabove-stated steps until the shot count number "n" is no longer lessthen the set interval time N. After that, the flow comes back to thestep 4a.

The third embodiment is arranged, as described above, to suspend thedriving action on the image sensing means and to turn off the electronicviewfinder when the shooting and recording actions are not performedduring the process of interval shooting. This saves the power source ofthe camera from being wasted.

FIG. 8 shows in outline the arrangement of an electronic still camerawhich is arranged as a fourth embodiment of the invention. FIGS. 9(a)and 9(b) are flow charts showing the operation control flow of theembodiment. FIGS. 10(a) and 10(b) are oblique views showing theelectronic still camera in a state of being operated by remote control.FIG. 10(a) shows the camera body and FIG. 10(b) shows a remote-controloperation member. In FIGS. 8 to 10(b), the same component parts as thoseof FIGS. 1 to 7 are indicated by the same reference numerals.

Referring to FIG. 8, a reference symbol E denotes remote-control modesetting means. The remote-control mode setting means includes a shootingmode selection switch 31 and a remote-control operation member 32 (FIG.10(b)). The electronic still camera (hereinafter referred to as camera)is arranged to be set into a remote-control shooting mode by theremote-control mode setting means, as will be described in detail later.Referring to FIGS. 10(a) and 10(b), these illustrations include a camerabody 34; a shutter release button 35; a viewfinder window 36; a tripod37; a remote-control operation member 32; and a shutter release button33 provided on the member 32.

The remote-control shooting operation is performed as described belowwith the normal shooting described in part along with the remote-controlshooting:

Like in the case of the normal shooting, the operator determines apicture composition for the remote-control shooting. The camera isfixedly set. After that, the shooting mode selection switch 31 isoperated to select the remote-control shooting mode. In this instance,the driving-suspending and displaying-off control means operates to turnoff the electronic viewfinder and to suspend the driving action on theimage sensor except when the release button 33 of the remote-controloperation member 32 is pushed for shooting and recording. With thecamera in the remote-control shooting mode, when the release button 33of the remote-control operation member 32 is pushed and the releasebutton 33 comes to the half stroke position thereof, the remote-controloperation member 32 sends to the camera body 34 a signal indicative ofthis in a known manner. When this signal is sensed on the side of thecamera body 34, the image sensor 4 is driven. The luminance of theobject to be recorded is measured by a light measuring unit which is notshown. When the release button 33 is further pushed till it comes to thefull stroke position thereof, a signal indicating the full strokepushing operation on the release button 33 is likewise sent to thecamera body 34. Upon sensing this signal by the control circuit of thecamera body 34, a shooting process begins. At first, the position of theiris 2 is adjusted to an aperture value which is either set according tothe luminance of the object or set beforehand by the photographer. Atthe same time, the shutter 3 is closed to discharge the electric chargeaccumulated by the image sensor 4. Then, the shutter 3 is operated and avideo signal stored at the image sensor 4 up to this point of time istransferred by the camera control circuit 26 to the recording part B1.The video signal is recorded by the recording part control circuit 24 onan unrecorded part of the recording medium. The shooting operation thencomes to an end. If the shooting mode is shifted under this condition tothe normal shooting mode by shifting the position of the shooting modeselection switch 31, the image sensor 4 is driven and the viewfinder 5is turned on to display an image sensed by the image sensor 4.

The flow of control over the operation of the fourth embodiment isbriefly described below with reference to the flow charts of FIGS. 9(a)and 9(b) with emphasis placed on the displaying-off control means:

Referring to FIGS. 9(a) and 9(b), the flow of control procedures beginswhen the power supply is switched on. At a step 101: The shooting modeof the camera is checked to find if it is the remote-control shootingmode. If not, the flow proceeds to a step 102. If so, the flow comes toa step 116. At the step 102: The image sensor and the electronicviewfinder are turned on. The shutter is opened. An automatic iriscontrol action is performed. The flow comes to a step 103. At the step103: Again, a check is made to see if the camera is in theremote-control shooting mode. If not, the flow comes to a step 105. Ifso, the flow proceeds to a step 104. At the step 105: A check is made tosee if the release switch (hereinafter referred to as switch) SW1 is on.If so, the flow comes to a step 106. If not, the flow comes back to thestep 103. At the step 106: The luminance of the object and a distance tothe object are measured. The power supply voltage and the white balanceare checked. At a step 107: A computing operation is performed for ashutter speed, an aperture value and the degree to which the position ofthe optical system is to be moved. The flow proceeds to a step 108. Atthe step 108: A check is made to see if the switch SW2 is on. If so, theflow comes to a step 110. At the step 110: The shutter is closed. At astep 111: The electric charge of the image sensor is discharged. Theposition of the iris and that of the optical system are moved. Step 112:The shutter is opened and closed. At a step 113: The electric charge istransferred. At a step 114: Recording is performed. At a step 115: Theshutter is opened. The automatic iris control action is performed. Theflow then comes back to the step 103. Further, with the camera found tobe in the remote-control shooting mode at the step 101, the flowbranches off from the step 101 to the step 116 as mentioned above. Atthe step 116: A check is made to see if the camera is in theremote-control shooting mode. If so, the flow proceeds to a step 117. Ifnot, the flow comes back to the step 102. At the step 117: A check ismade to see if the release button 33 is pushed to its half-strokeposition. If so, the flow proceeds to a step 118. If not, the flow comesback to the step 116. At the step 118: The luminance and distance of theobject are measured. The power supply voltage and white balance arechecked. At a step 119: A computing operation is performed for a shutterspeed, an aperture value and the degree to which the position of theoptical system is to be moved. The flow then comes to a step 120. At thestep 120: A check is made to see if the release button 33 is pushed toits full-stroke position. If so, the flow comes to a step 122. If not,the flow comes to a step 121. At the step 121: A check is made to see ifthe release button 33 is pushed to its half-stroke position. If so, theflow comes back to the step 120. If not, the flow comes back to the step116.

At the step 122: The image sensor is driven. The shutter is closed. At astep 123: The electric charge of the image sensor is discharged. Theposition of the iris and that of the optical system are moved. At a step124: The shutter is opened and closed. At a step 125: The electriccharge is transferred. At a step 126: Recording is performed. At a step127: The image sensor is turned off. The flow then comes back to thestep 116. Further, at the step 104, the image sensor and the electronicviewfinder are turned off before the flow comes to the step 117.

Next, a fifth embodiment is described below with reference to FIGS. 11,12, 13(a) and 13(b):

FIG. 11 shows in outline the arrangement of an electronic still camerawhich is arranged according to this invention as the fifth embodimentthereof. FIG. 12 shows the circuit arrangement of the fifth embodiment.FIGS. 13(a) and 13(b) are flow charts showing the operation control flowof the fifth embodiment. In FIG. 11, the component parts which are thesame as or equivalent to those of FIGS. 1 to 10(b) are indicated by thesame reference numerals. A remote-control operation member 38 isarranged to be attachable to and detachable from the camera body. Arelease button 39 is disposed at the remote-control operation member 38.An engagement confirmation unit 40 is provided on the camera body forconfirming that the remote-control operation member 38 is engaged withthe camera body. The unit 40 and a remote-control operation memberengaging state confirming circuit 60 (FIG. 12) jointly form engagementconfirming means G for confirming that the remote-control operationmember 38 is detached to or removed from the camera body.

The fifth embodiment operates as described below with reference to FIGS.11, 12, 13(a) and 13(b):

The operation of the fifth embodiment is similar to that of the fourthembodiment described in the foregoing in a case where the remote-controloperation member 38 is attached to the camera body. However, theoperation under that condition is once again described here. Referringto FIG. 11, when the power supply is turned on with the switch 7operated, an image formed at the image sensor 4 is displayed on theelectronic viewfinder 5. At this moment, the shutter 3 is open. Further,the iris 2 is opened or closed according to the amount of electriccharge accumulated at the image sensor 4, i.e., according to thequantity of light incident on the image sensor 4. The quantity ofincident light is thus adjusted by means of the iris 2. With a picturecomposed by the photographer through the electronic viewfinder 5, therelease button 35 which is shown in FIG. 10(a) is pushed for shooting.When the release button 35 is pushed to its half-stroke position, theswitch SW1 (FIG. 12) is turned on. This causes the image sensor 4 to bedriven. The luminance of an object to be shot is then measured by alight measuring unit which is not shown. When the release button 35 isfurther pushed to reach to its full-stroke position, the switch SW2(FIG. 12) is turned on. The on-state of the switch SW2 is confirmed bythe camera control circuit 26. This causes the process of shooting tobegin. First, the position of the iris 2 is moved to an apertureposition corresponding to an aperture value which is either determinedby the luminance of the object or predetermined by the photographer. Atthe same time, the shutter 3 is closed. The electric charge accumulatedat the image sensor 4 is discharged. The shutter is opened and closed.Then, a video signal accumulated and formed at the image sensor 4 istransferred by the camera control circuit 26 to the recording part B1.The video signal is recorded by the recording part control circuit 24 onan unrecorded part of a recording medium. The shutter is brought back toits state obtained before it is released, and the shooting process comesto an end.

In a case where none of camera operation members such as the releasebutton 35 are operated over a certain period of time, a power supply tothe electronic viewfinder 5 is turned off to prevent the electric energyof the power source from being wasted. However, when any of the cameraoperation members comes to be operated under this condition, theelectronic viewfinder 5 is again turned on to bring it back to itsprevious state.

While the normal operation of the fifth embodiment is as describedabove, its operation in the remote-control shooting mode is as follows:

In the remote-control shooting mode, the camera is fixed in positionafter a picture is composed by the photographer like in the normalshooting. After that, the remote-control operation member 38 is detachedfrom the camera. The detachment of the remote-control operation member38 is confirmed by the engagement confirmation unit 40. The camera isthen set into the remote-control shooting mode. The electronicviewfinder 5 is then turned off and the image sensor 4 ceases to bedriven until shooting and recording are performed by pushing the releasebutton 39 (which corresponds to the release button 33 of FIG. 10(b)) ofthe remote-control operation member 38 (which corresponds to the member32 of FIG. 10(b)). While the camera is in the remote-control shootingmode, when the release button 39 is pushed and comes to its half-strokeposition, the remote-control operation member 38 sends, in a knownmanner, a signal to the camera body indicating that the release button39 is pushed to the half-stroke position. When this signal is sensed bythe camera body, the image sensor 4 is driven. Then, the luminance ofthe object is measured by the light measuring unit (not shown). With therelease button further pushed, when it reaches its full-stroke position,the remote-control operation member 38 likewise sends another signal tothe camera body indicating that the release button 39 has reached itsfull-stroke position. With that signal sensed by the control circuit ofthe camera body, the process of shooting begins. The ensuing part of theoperation is similar to the normal shooting. However, it is furtherdescribed as follows:

In the first place, the iris 2 is moved to its position of either anaperture value determined according to the luminance of the object or anaperture value preset by the photographer. At the same time, the shutter3 is closed. A video signal accumulated at the image sensor 4 istransferred by the camera control circuit 26 to the recording part B1.The recording part control circuit 24 then records the video signal onan unrecorded part of the recording medium, and the process of shootingcomes to an end. Further, under this condition, when the remote-controloperation member 38 is attached again to a given part of the camera bodyand when this is confirmed by the engagement confirmation unit 40, thecamera comes back to the normal shooting mode. Then, the electronicviewfinder 5 is turned on to display an image obtained by the imagesensor 4.

Next, the operation of the fifth embodiment is controlled as describedbelow with reference to FIGS. 13(a) and 13(b) which are flow charts:

The flow charts of FIGS. 13(a) and 13(b) differ from those of FIGS. 9(a)and 9(b) in that: The steps 101, 103 and 116 of FIGS. 9(a) and 9(b) arereplaced with the steps 101A, 103A and 116A of FIGS. 13(a) and 13(b)respectively. More specifically, the words "remote-control shootingmode?" of FIGS. 9(a) and 9(b) are changed to "remote control operationmember detached from camera?" in the flow charts of FIGS. 13(a) and13(b). Since both the fourth and fifth embodiments are described asbeing set in the remote-control shooting mode, the operation controlsteps of the fifth embodiment are executed in the same manner as in thecase of the fourth embodiment with the exception of the above-statedchange in wording. Therefore, the operation control procedures of thefifth embodiment which are the same as those of the fourth embodimentare omitted from the description given here. Further, the release button39 mentioned at the steps 117A, 120A and 121A of FIG. 13(b) correspondsto and is equivalent to the release button 33 mentioned at the steps117, 120 and 121 of FIG. 9(b) as mentioned in the foregoing.

The fourth and fifth embodiments described above are arranged to suspendthe driving action on the image sensing means and to turn off theelectronic viewfinder while the camera is in the remote-control shootingmode except when shooting and recording are to be performed in thismode. This arrangement effectively prevents the power source of thecamera from being unnecessarily consumed.

What is claimed is:
 1. An electronic still camera comprising:a) aphoto-taking optical system detachably mounted on a camera body of saidcamera; b) image sensing means for converting into an electrical videosignal an object image formed by said photo-taking optical system; c)recording means for recording the video signal; d) an electronicviewfinder attached to said camera body and arranged to display theimage obtained by said image sensing means when photo-taking can beeffected; e) detecting means for detecting a detached or mounted stateof said photo-taking optical system; and f) control means arranged toturn off said electronic viewfinder when said detecting means detectsthe detached state of said optical system from the camera body.
 2. Acamera according to claim 1, wherein said control means is arranged tocause said electronic view finder to be turned on again to display animage represented by the video signal obtained by said image sensingmeans when said photo-taking optical system is mounted on the camerabody after said photo-taking optical system had been detached from saidcamera body.
 3. A camera according to claim 1, wherein said controlmeans is arranged to suspend a driving action on said image sensingmeans when the detached state of said photo-taking optical system fromsaid camera is detected by said detecting means.
 4. An electronic stillcamera comprising:a) a photo-taking optical system; b) image sensingmeans for converting into an electrical video signal an object imageformed by said photo-taking optical system; c) recording means forrecording the video signal; d) an electronic viewfinder for displayingan image represented by the video signal obtained by said image sensingmeans; e) self-timer means arranged to perform a self-timer operation;and f) control means for turning off said electronic viewfinder when theself-timer operation begins.
 5. A camera according to claim 4, whereinsaid control means is arranged to cause said electronic viewfinder to beturned on again to display an image represented by the video signalobtained by said image sensing means after the completion of theself-timer operation.
 6. An electronic still camera comprising:a) aphoto-taking optical system; b) image sensing means for converting intoan electrical video signal an object image formed by said photo-takingoptical system; c) recording means for recording the video signal; d) anelectronic viewfinder for displaying an image represented by the videosignal obtained by said image sensing means; e) interval shooting meansfor automatically performing an interval shooting action at intervals ofa preset period of time and for a preset number of pictures; and f)control means arranged to turn off said electronic viewfinder, exceptwhen shooting and recording actions are performed, after commencement ofthe interval shooting action in an interval shooting mode.
 7. A cameraaccording to claim 6, wherein said control means is arranged to suspenda driving action on said image sensing means concurrently when saidelectronic viewfinder is turned off.
 8. An electronic still camerahaving a photo-taking optical system, image sensing means for convertinginto an electrical video signal an object image formed by saidphoto-taking optical system, recording means for recording the videosignal, an electronic viewfinder for displaying an image represented bythe video signal obtained by said image sensing means, and aremote-control shooting function, comprising:a) remote-control modesetting means for setting said camera into a remote-control shootingmode; and b) control means for turning off said electronic viewfinderwhen said camera is set in the remote-control shooting mode by saidremote-control mode setting means.
 9. A camera according to claim 8,wherein said remote-control mode setting means includes a remote-controloperation member which can be engaged with a camera body, and engagementconfirming means for confirming the engagement of said remote-controloperation member with said camera body.
 10. A camera according to claim9, wherein said camera is set into the remote-control shooting mode whendisengagement of said remote-control operation member from said camerabody is confirmed by said engagement confirming means at the time of ashootable state of said camera.
 11. A camera according to claim 8,wherein said remote-control mode setting means is arranged to set saidcamera into the remote-control shooting mode by using a remote-controlshooting mode setting switch disposed on a camera body at the time of ashootable state of said camera, and wherein said camera is arranged tocarry out a remote-control shooting operation by using a remote-controloperation member which is arranged separately from said camera body. 12.A camera according to claim 8, wherein said control means is arranged tosuspend a driving action on said image sensing means concurrently whensaid electronic viewfinder is turned off, except when a shootingoperation is performed.